selenium - 用例执行失败后自动截图（装饰器）

循序渐进的方式介绍（也可以直接到步骤4中看示例模板）

1. 简单示例：

from selenium import webdriver
import time
driver = webdriver.Chrome()


def get_screen():
    now_time = time.strftime('%Y_%m_%d_%H_%M_%S')
    driver.get_screenshot_as_file(f'{now_time}.jpg')


def screen(func):   # 自动截图装饰器
    def inner(*args, **kwargs):  # 由于我们不知道被调用的函数到底有几个参数，写一个万能装饰器，传可变参数
        try:
            f = func(*args, **kwargs)
            # return f
        except:
            get_screen()   # 失败后截图
            # raise
    return inner


@screen   # 加装饰
def search(driver):
    driver.get('http://www.baidu.com')
    driver.find_element_by_id('kw11').send_keys('python')  # id不对，会运行失败
    driver.find_element_by_id('su').click()
    time.sleep(5)
    driver.quit()


search(driver)  # 执行

以上代码，会发现driver作为全局变量存在，无法传入装饰器中。同时，也没有和unittest结合。我们对此进行改良。 

2. 不带参数的装饰器

• 被装饰的函数，传入__init__()
• 调用被装饰的函数时，自动调用__call__()

__init__()里是初始化参数，__call__()里是原函数参数

class decoratorWithoutArguments(object):
    def __init__(self, f):    # 被装饰的函数，传入__init__()
        print('inside __init__()')
        self.f = f

    def __call__(self, *args):   # 调用被装饰的函数时，自动调用__call__()
        print('inside __call__()')
        self.f(*args)
        print('after self.f(*args)')


@decoratorWithoutArguments  # 不带参数
def say_hello(a1, a2):
    print('say hello arguments: ', a1, a2)


say_hello(2, 3)

运行结果如下：

inside __init__()
inside __call__()
say hello arguments: 2 3
after self.f(*args)

3. 带参数的装饰器

• 参数写到__init()__里
• 被装饰的函数传入__call()__

class decoratorWithArguments(object):
    def __init__(self, arg1, arg2, arg3):  # 传入装饰器参数
        print('inside __init__()')
        self.arg1 = arg1
        self.arg2 = arg2
        self.arg3 = arg3

    def __call__(self, f):   # 可以只给它传一个参数 -- 被装饰的函数
        print('inside __call__()')
        
        def wrapped_f(*args):
            print('inside wrapped_f()')
            print('decorator arguments: ', self.arg1, self.arg2, self.arg3)
            f(*args)
            print('after f(*args)')
        return wrapped_f


@decoratorWithArguments('hello', 'world', 42)  # 带参数
def say_hello(a1, a2, a3, a4):
    print('say_hell0 arguments: ', a1, a2, a3, a4)


say_hello(1, 2, 3, 4)

运行结果如下：

inside __init__()
inside __call__()
inside wrapped_f()
decorator arguments: hello world 42
say_hell0 arguments: 1 2 3 4
after f(*args)

so，可以尝试按此方法，将浏览器驱动传入装饰器中

4. 结合unittest

 百度首页为例，有异常时截图，代码如下：

from selenium import webdriver
import unittest
import time


class Screen(object):
    def __init__(self, driver):
        self.driver = driver

    def __call__(self, func):
        def inner(*args, **kwargs):
            try:
                return func(*args, **kwargs)
            except:
                now_time = time.strftime('%Y_%m_%d_%H_%M_%S')   # 异常时，截图
                self.driver.get_screenshot_as_file(f'{now_time}.png')
                raise   # 抛出异常，不然会认为测试用例执行通过
        return inner


class MyTest(unittest.TestCase):
    driver = webdriver.Chrome()

    @classmethod
    def setUpClass(cls):
        cls.driver.get('http://www.baidu.com')

    @Screen(driver)
    def test_01(self):
        self.driver.find_element_by_id('kw').clear()
        self.driver.find_element_by_id('kw').send_keys('python')
        self.driver.find_element_by_id('su1').click()  # id不对，会报错
        time.sleep(3)

    @Screen(driver)
    def test_02(self):
        self.driver.find_element_by_id('kw').clear()
        self.driver.find_element_by_id('kw').send_keys('selenium')
        self.driver.find_element_by_id('su').click()
        time.sleep(3)

    @classmethod
    def tearDownClass(cls):
        cls.driver.quit()


if __name__ == '__main__':
    unittest.main()

截图如下：